Antifoam preparation for aqueous systems

ABSTRACT

The present invention relates to an antifoaming preparation for aqueous systems consisting essentially of a water insoluble organic liquid, e.g., mineral oil; a filler; a hydroxyl endblocked organopolysiloxane or a benzene soluble organopolysiloxane resin; and an ingredient, e.g., KOH, a hydrocarbon amine, ammonia, or hexamethyldisilazane which would lend compatibility between the filler and the silicone fluid or silicone resin component. The preparations in question would be particularly useful in the pulp and paper industry.

United States Patent Keil 51 May 30, 1972 541 ANTIFOAM PREPARATION FOR3,076,768 2/1963 Boylan ..2s2/3sa AQUEOUS SYSTEMS I PrimaryExaminer-John D. Welsh Inventor; J p Ken, Mldlandv Mlch- Attorney-RobertF. Fleming, Jr., Laurence R. Hobey, Harry {73] Assignee: Dow CorningCorporation, Midland, Mich. Dmgman and Joseph Radz'us 22 Filed: Mar. 16,1970 57 ABSTRACT [21] Appl. Nos 20,040 The present invention relates toan antifoaming preparation for aqueous systems consisting essentially ofa water insoluble 52] U S Cl 252/358 252/32] organic liquid, e.g.,mineral oil; a filler; a hydroxyl endblocked [51] 1". .cl 86 17/00organopolysiloxane or a benzene soluble organopolysnoxane 58] l I358 321resin; and an ingredient, e.g., KOH, a hydrocarbon amine. am- ,7 V V Vmonia, or hexamethyldisilazane which would lend compati- [56] ReferencesCited bility between the filler and the silicone fluid or silicone resincomponent. The preparations in question would be particu- UNITED STATESPATENTS larly useful in the pulp and P p industry- 3,033,789 5/1962Asseff ..252/358 4Clalrns, No Drawing ANTIFOAM PREPARATION FOR AQUEOUSSYSTEMS This invention relates to antifoaming or defoarning compositionswhich are particularly useful for preventing or abating foams in aqueoussystems.

Foaming and frothing, which are principally due to entrap ment ofvarious vapors, are encountered at the surface of many liquids.Applications in which undesirable foams exist are extremely diverse,with problems ranging from unesthetic foams to foams hazardous to life.Foam problems and their resolutions have been frequently reported inpolymerization, paint processing, fermentation, sugar refining, oil wellpumping, food preparation, steam generation, sewage disposal, textiledyeing, adhesive processing, and conversion of ores refined byflotation.

Typically, foaming problems are a constant source of disruption inalkaline pulping processes. The alkaline pulping processes generallyconsist of the soda and kraft or sulfate processes and are alkaline innature because sodium hydroxide or caustic are normally employed in theformer and sodium sulfate or salt cake and sodium hydroxide are used inthe latter. These processes currently represent the most utilizedpumping procedures in the pulp and paper industry and a factor inherentin their continued acceptance and growth is that the spent chemicals canbe readily reclaimed, thus providing an economic advantage over otherconceivable methods. In spite of the above, an important disadvantageexists in that extensive foam occurs during the pulp washing, screening,and knotting operation which deleteriously affects the various phases ofproduction. I

ln accordance with the above, it is an object of this invention toprovide a novel antifoaming preparation which prevents or abatesundesirable foam in aqueous systems.

Another object of the present invention is the provision of a novel,inexpensive defoamer composition formed of readily available inexpensivematerials and having an efi'ectiveness, comparable to or superior to,presently available commercial antifoamers and defoamers.

The nature of the invention as well as other objects and advantagesthereof will be readily apparent from a consideration of the followingdetailed description.

This invention relates to an antifoaming agent for aqueous systemsconsisting essentially of a mixture of A. 100 parts by weight of a waterinsoluble organic liquid which is a member selected from the groupconsisting of mineral oil, esters of carboxylic acids and monohydricalcohols, alcohols containing from 5 to 18 carbon atoms inclusive,polyoxypropylene and polyoxybutylene glycols, triorganophosphates,vegetable oils, and sperm oil,

B. from 0.5 to 10.0 parts by weight of an organopolysiloxane compoundwhich is a member selected from the group consisting of a' hydroxylendblocked dirnethylpolysiloxane fluid having a viscosity of at least 35centistokes at 25 C. and a benzene soluble organopolysiloxane resinconsisting essentially of 1 SiO units and 2 R SiO units in which R is amonovalent hydrocarbon radical containing from 1 to 6 carbon atomsinclusive, and in which the ratio of 1 units to 2 units is within therange of from 1.2/1 to 0.6/1,

C. from 0.5 to 10.0 parts by weight of a filler which is a memberselected from the group consisting of a finely divided silica and amethylsilsesquioxane gel, and

D. from 0.002 to 5.0 parts by weight of a compound which is a memberselected from the group consisting of a hydrocarbon amine, ammonia, adisilazane of the formula and a compound of the formula R'Ol-l in whichR is an alkali or alkaline earth metal.

As noted above, R can be any monovalent hydrocarbon radical containingfrom I to 6 carbon atoms such as the methyl, ethyl, propyl, isopropyl,butyl, isobutyl, t-butyl, arnyl, hexyl, vinyl, ally], cyclohexyl, andthe phenyl radical, among others, whereas R can be an alkali or alkalineearth metal such as potassium, sodium, lithium, cesium, magnesium,calcium or strontium.

illustrative examples of the water insoluble organic liquid (A) aremineral oil, and preferably a mineral oil that is high in paraffincontent and which is in the viscosity range of from to 300 SSU at 100F.; esters of carboxylic acids and monohydric alcohols such as dioctylphthalate, diethyl succinate, methyl caproate, butyl pelargonate, ethylstearate, nonyl stearate, dodecyl laurate, methyl melissate, etc.,;alcohols containing from 5 to l8 carbon atoms such as amyl alcohol,decyl alcohol, dodecyl alcohol, pentadecyl alcohol, and octadecylalcohol; polyoxypropylene and polyoxybutylene glycols; triorganophosphates such as tributyl phosphate and tributoxyethyl phosphate; andvegetable oils such as peanut oil, coconut oil, olive oil, cottonseedoil, and linseed oil, among numerous other; and sperm oil.

If any of the above materials (A) are initially in a solid state, it isnecessary that the materials be dispersed in a suitable mutual solventfor (A) and (B), and said mutual solvent may function solely as adispersing medium to facilitate the production of the defoaming agent.

The organopolysiloxane components designated as (B) are well known andare readily available commercial materials. For example, the benzenesoluble organopolysiloxane resin can be prepared by merely reacting asilica hydrosol having a pH of less than 5 with an organosiliconcomposition composed of groups of the formula RnS Xl-n and RsSlO inwhich R is alkyl, monocyclic aryl hydrocarbon, and halogenatedmonocyclic aryl hydrocarbon, X is chlorine or alkoxy, and n has a valueof from 1 to 3, the average degree of substitution of said compositionbeing from 2.1 to 3 R groups per silicon atom and at least 50 percent ofthe R groups being alkyl, in amount such that there is at least one molof organosilyl groups per mol of SiO in the silica hydrosol. Thereaction proceeds rapidly at 30 C. or above to produce copolymericsiloxanes. During the reaction the mixture is preferably thoroughlyagitated. After completion of the reaction, an emulsion forms whichseparates into two layers upon standing. The layers are then separatedand the resin'noted above is washed free of acid and dried.

The essential characteristics of the aforesaid organopolysiloxane resinas defined above are the siloxane units present, the ratio of thesesiloxane units, the fact that the organopolysiloxane is a benzenesoluble resin.

The silica designated (C) above is a finely divided silica, e.g.,precipitated silicas, fumed silicas, and the like. The silica aerogelemployed in the composition of this invention can be prepared bydisplacing water from a hydrogel in such a manner as to avoid excessiveshrinking or crushing of the cellular structure of the material. Amethod of preparing the silica, which method consists essentially indisplacing water from silica gel with a low boiling organic liquid suchas ethyl alcohol, or diethyl ether, heating the treated gel in anautoclave to approximately the critical temperature of the organicliquid, releasing vapors of the latter from the autoclave and finallyevacuating the autoclave while hot and charged with the residual gel, isdescribed by S. S. Kistler in J Phys. Chem. 36, 52-64 (1932). Finelydivided silica which is quite suitable for use in this invention iscommercially available.

The methylsilsesquioxane gel (C) is also well known and is readilyprepared by slowly adding methyltrimethoxy silane to water containingalkali such as NaOH, KOl-l, or the like. As the methyltrimethoxysilaneis added, it instantaneously gels or coagulates. The gel is then washedfree of alkali and dewatered (centrifuged). Preferably the gel isthereafter pulverized so that more surface area is exposed, thusenhancing the performance of the finished preparation.

As noted above, (D) may be ammonia, hexamethyldisilazane, or ahydrocarbon amine such as brucine, sec-budiethylamine, dimethylamine,

ginine, L-lysine, aconitine, benzylamine, cinchonidine, codeine,coniine, emetine, o-methoxybenzylamine, mmethoxybenzylamine,p-methoxybenzylamine, t-butyl-4- isonitrosoamylamine, t-octylamylamine,t-octyl-2-(beta-butoxyethoxy) ethylamine,2,4,6-tris-(dimethylamino)phenol, aniline, phenylhydrazine, pyridine,quinoline, p-bromophenylhydrazine, n-nitro-o-toluidine,beta-ethoxyethylarnine, tetrahydrofurfurylamine, m-arninoacetophenone,iminodiacetonitrile, putrescine, spermin, gamma-N,N-

dimethylaminopropylpentamethyldisiloxane, p-toluidine, and veratrine.

The amount of the organopolysiloxane compound (B) employed need only besufficient to effect the desired defoaming and can vary depending uponthe particular water insoluble liquid (A) which is selected. Although arange of from 0.5 to 10.0 parts by weight has been found to be suitable,a range of from about 2.0 to about 5.0 parts by weight has been found tobe preferable. More than 10.0 parts by weight can be feasibly used;however, it is not recommended in view of economic considerations andthe like.

From 0.5 to 10.0 parts by weight of the filler (E?) .Ha' 'ii employed,and a range of about 2.0 to about 5.0 parts by weight is preferred. Toolittle or too much of the filler (C) lends an improper inconsistency tothe mixture which has an ultimate effect upon its performancecharacteristics and/or utility.

From 0.002 to 5.0 parts by weight of the compound (D), e.g., the amine,ammonia, the hexamethyldisilazane, KOH, or the like, has been found tobe satisfactory for purposes of the present invention; however, a rangeof from about 0.02 to about 1.0 parts by weight is particularlysuitable. The amount of the compound (D) employed has a critical effectupon compatibility of the mixture and if the amount used falls withoutthe recited limits, the performance of the mixture is detrimentallyaltered.

It is to be noted that one can include a surfactant in the defoamers ofthis invention to allow the water insoluble organic liquid to spread atthe air-water interface. Anionic, cationic, or non-ionic spreadingagents will effectively function in this manner and the type to beselected generally is dependent upon the particular system in which itis to be employed. It should be added, of course, that other additives,e. g., rust inhibitors, emulsifiers, or the like may also be included ifdesired to impart specific properties where required.

The best means for preparing the mixture of the present inventioninvolves adding an admixture of the organopolysiloxane compound (B),e.g., the hydroxyl endblocked dimethylpolysiloxane and the compound (D),e.g., triethylenetetramine to the water insoluble organic liquid (A),e.g., mineral oil. The above is stirred or otherwise physically mixed toinsure that a homogeneous dispersion exists and then the tiller (C) isappropriately added. The entire mixture is then sheared by anyacceptable means, e.g., a colloid mill and thereafter may or may not beheated to a moderate temperature (about C.) to assure that the fillerparticles are completed wetted.

It is to be further noted that the quantity of defoaming agent to beintroduced to the liquid medium which presents a foaming problem is notespecially critical with the exception that it must be incorporated inan amount sufficient to effectively collapse the foam. It is obviousthat the amount of defoaming agent employed is dictated by the amount offoam present and how rapidly one wishes to rid the medium of the foam,however, for purposes of the present invention it has been found thatapproximately onedrop of agent per 100 ml. of liquid medium ordinarilywill sufiice in most situations.

Depending upon the specific mode of application, the compositionsdefined herein can act as either defoarners or antifoamers. Defoarningagents are foam reducers or palliatives whereas antifoaming agents arefoam-prevention materials. Hence when the foam is present in the fluidmedium and it is expedient to reduce this foaming, addition of anappropriate amount of the compositions of this invention will arrestfurther foaming and reduce the foaming present at that time. When onedesires to prevent foaming prior to its commencement, the addition ofthe defoaming agent during the preparation of the fluid medium willretard the anticipated foaming problem that would ordinarily be expectedto occur.

The following examples are merely illustrative and are not intended tolimit the invention which is properly delineated in the appended claims.

To determine defoaming ability, a hand shaking modified test wasperformed by adding the defoarner to 100 cc. of 1.0 percent solution ofisooctyl phenyl polyethoxyethanol, a commercially available surfaceactive agent, in an 8 ounce round bottle, and then shaking the cappedbottle back and forth through an arc of 90 for 12 shakes. The timerequired for clear liquid to appear through the foam on the top liquidsurface was noted as the defoaming time.

Efficiency of the defoaming agents to simulate conditions in the pulpindustry were evaluated by testing their ability to defoam concentratedblack liquor obtained from a paper mill having approximately 16 percentby weight solids. The apparatus used in evaluating the foamingcomposition can be described as follows. A beaker of 2,000 cc. capacityis used. A curved outlet fused onto the base of the beaker is connectedwith a rubber hose to a centrifugal pump. The pump is used tocontinuously cycle the concentrated black liquor from the beaker to thepump and back into the beaker. The pumping is carried out at a rate sothat the black liquor in the beaker is agitated by the reentering liquidto such an extent that the formation of foam appears. In practice therate is about two gallons per minute. The concentrated black liquorenters the beaker at a point about 4 541 inches above the surface of theliquid in the beaker and strikes the surface of the liquid in the beakerat an angle of 90.

In carrying out the testing of the defoarner composition, 1,000 cc. ofconcentrated black liquor at F. which contained about 16 percent byweight of solids was placed in the beaker of the apparatus. This liquid,when quiescent and at a temperature of 180 F filled the beaker to alevel of about 3 V4 inches from the top. Sixty parts per million of thedefoaming composition was added to the beaker containing 1,000 cc. ofthe aforesaid concentrated black liquor. The concentrated black liquorwas warmed to maintain the temperature at approximately 180 F. and wasat this temperature during the operation of the test. In operation, thepump and stop watch were started simultaneously. The time in seconds forthe foam to rise and overflow the beaker was recorded. This time is anindication of the defoaming ability of the defoarner which is beingtested. The longer for the foam to overflow the beaker, the better isthe defoaming action of the defoarner.

EXAMPLE 1 Using the defoaming agents listed below in accordance with thehand shaking modified test described above, the followin resu ts r olztan dt a Water insoluble organic g Snmplc liquid (A) Organopolysiloxanecompound (B) Filler (C) Compound (D) nbnto (l) 100 parts mineral oil..."2.0 parts hydroxyl endblocked dimethylpolysiloxane fluid, 5.0 parts 0.2pnrt triothvlene 15 secs.

35-40 centistolres. silicn. totrnminoi (2) .do 1.0 part oi a benzenesoluble organopolysiloxane resin consistd 1.0 purl; hpxalnpfllyl 2 S095ing of (CHQaSiOm units and SiO: units in which the ratio (iisilnznno. of(CH3)3SiOl/2 units to the S102 units is within the range from 06/1 to1.2/1. (3) ,do 0.5 part of a benzene soluble organopolysiloxane resinconsistdo.... 1.5 parts liexamethyisecs ing of (CH;) Si01 z units andS102 units in which the ratio disiluzano. 0i (CH3) 3810112 units to theS102 units is within the range from 0.6/1 to 1.2/1. (4) 100 parts spermoil 1.0 part of a benzene soluble organopolyslloxanc rosin consist-.do...... 1.0 port hoxnniothyl- 24 secs.

ing of (CH3)3S10i/Q units and 810: units in which the ratio disilnznnu.oi (CH SiO| g units to the 810: units is within the range from 0.6/1 to1.2/1. (5) 100 parts mineral oil"... 2.0 parts of a benzene solubleorganopolysiloxnnn rosin ('nn- 5.0 ports 0.02 pnrt K011 2 sons Sistillil0f a)aSiO1/: units and S: units in which tho mothylsil- 7 ratio oi(CHmSiOm units to tho S102 units is within ihn sosquioxnnn range from0.6/1 to 1.2/1. gel. (6) 100 parts polyoxypropyl- 1.0 part of a benzenesoluble organopolysiloxano rosin con- 5.0 parts silica. 1.0 porthoxmnoihylsecs.

ene glyco sisting of (CH3)3SlOl/2 units antiSiOz units in which thedisilnzanc.

ratio of (CHalaSiOm units to the S102 units is within the range from0.6/1 to 1.2/1. (7) 100 'parts trioctyl phos- 5.0 parts of a benzenesoluble organopolysiloxanc resin con 10.0 parts 1.0 port hexarnethyl- 6secs.

phate. sisting of (CHzOaSiOr/e units and S102 units in which the silica.disilazane.

ratio of (OHmSiOi z units to the S102 units is within the range from0.6/1 to 1.2/1. (8) 100 parts coconut oil... 6.0 parts hydroxylendblocked dimethylpolysiloxane fluid, 5.0 parts silica. 4.0 partshexamethylsecs.

. 3H0 centistokes. I disilazane. (9) 100 parts dioctyl 8.0 partshydroxyl endblockcd dlmethylpolysiloxane fluid, 5.0 parts silica. 2.0parts hexamethyl- 6 secs.

phthalate. -40 centistokes. I disilazane. (10) 100 parts mineral oil10.0 parts hydroxyl endblocked dimethylpolysiloxaue fluid, 5 0 partssilica. 2.0 parts hexamethyl- 30 secs. 2,000 centistokes. disilazane.(1i) 100 parts mineral oil.-." 2.02 gggts hydtroliyl endbloekeddimethylpolysiloxane fluid, 5.0 parts silica. 2.0 parts ammonia- 90secs.

, centis 0 es. (i2) 100 parts mineral oil 10.0 parts oi a benzenesoluble organopolysiloxane resin con- 5.0 parts silica. 0.05 part KOH 2secs.

sisting of (CHzDaSiOm units and 5102 units in which the ratio of(CH3)3Sl.O1/2 units to the SiOz units is within the range irom 0.6/1 to1.2/1. (13) 100 parts decyl alcohol. 5.0 parts of a benzene solubleorganopolysiloxane resin con- 5.0 parts silica. 2.0 parts hexamethyl- 15secs.

sisting of (CHmSiOm units and S102 units in which the silazane. ratio oi(CH ):4SiO1/z units to the S102 units is within the range from 0.6/1 to1.2/1. (14) 100 parts mineral 011..... 0.5 part of a benzene solubleorganopolysiloxane resin con- 0.5 part silica 0.5 part hexamethyl- 35secs.

sisting of (CHahSiOi z units and S102 units in which the disilazane.ratio oi (CH3)3SlOi/2 units to the S102 units is within the range from0.6/1 to 1.2/1.

when a commercially available black liquor deioamer was used as acontrol, it took greater than 480 seconds for the foam to abate.

EXAMPLE 2 Control (commercially available 30 seconds for foam defoamer)to overflow When the following benzene soluble organopolysiloxane Samplei Example i 180 seconds for foam resins were substituted for thecorresponding benzene soluble 40 S l 5 E l ia f f organopolysiloxaneresin of Example 1 within the indicated amp H xamp e m :32? or ranges,substantially equivalent results were obtained.

EXAMPLE 5 (A) CH! When the following materials were substituted for thecorresponding materials in the various samples of Example 1, "510m unitsand substantially equivalent results were obtained.

in. (B) CH3 WATER INSOLUBLE o ORGANIC LIQUID (A) COMPOUND (D) cm=c11s101/, units and s10: units 5 Diethyl succinate Cocaine Methyl caproateEthylamine 3 Dodecyl laurate Hydrazine Ethyl stearate Methylamine CHaCHnits and units Pentadecyl alcohol n-Propylamine CH3 Polyoxybutyleneglycol Ernetine Tributoxyethyl phosphate p-Toluidine (D) CH: Peanut oilVeratrine l Olive oil NaOH -a) a $101!: units S 101/: Units Cottonseedoil UO 4 Linseed oil Mg(OH),

and SiO, units in which the ratio of the respective units are 0.5 Thatwhich is daimed is! i to 025 to 1 1 I. An antifoaming agent for aqueoussystems consisting cs sentially of a mixture of EXAMPLE 3 A. 100 partsby weight of a water insoluble organic liquid which is a member selectedfrom the group consisting of w endblocked dlmethylpolyslloxane flmdsmineral oil, esters of carboxylic acids and monohydric alhavmgviscosities of 50, 100, L000, 12,500 and 25,000 centistokes weresubstituted for the corresponding fluids of cohols alcohols contammgfrom 5 to 18 carbon atoms In usive l ox but lene l cols, trior ano hoshates, Example 1, substantially equivalent results were obtained. cl y yy y g p p vegetable oils, and sperm Oil, I EXAMPLE 4 B. from 0.5 to 10.0parts by weight of an organopolysiloxane compound which is a memberselected from the When using the test described above to determineefficiengroup consisting f a h d l dbl k d di gh l. cy of the defoamingagents in the Kraft process, the following polysiloxane fluid having aviscosity of at least 35 results were obtained centistokes at 25 C. anda benzene soluble organopolysiloxane resin consisting essentially of (1)SiO, units and (2) R Sio units in which R is a monovalent hydrocarbonradical containing from 1 to 6 carbon atoms inclusive, and in which theratio of 1 units to 2 units is within the range offrom 1.2/1 to 0.6/1,and

C. from 0.5 to 10.0 parts by weight of a filler which is a memberselected from the group consisting of a finely divided silica and amethylsilsesquioxane gel, and

D. from 0.002 to 5.0 parts by weight of a compound which is a memberselected from the group consisting of ammonia, a disilazane of theformula in which the ratio of (CHQ SiO units to the SiO, units is withinthe range from 0.6/1 to 1.2/1,

C 2.5 parts by weight silica, and

D 1.0 part by weight hexamethyldisilazane.

3. The antifoaming agent as recited in claim 1 which consistsessentially of a mixture of A parts by weight mineral oil,

B 2.0 parts by weight of a benzene soluble organopolysiloxane resinconsisting of (CH ),SiO,,- units and SiO, units in which the ratio of(CH SiO units to the SiO, units is within the range from 0.6/1 to 1.2/1,v

C 5.0 pans by weight methylsilsesquioxane gel, and

D 0.02 part by weight KOH.

4. The antifoaming agent as recited in claim 1 which consistsessentially of a mixture of A. lOO parts by weight dioctyl phthalate,

B. 5.0 parts by weight hydroxyl endblocked dimethylpolysiloxane fluidhaving a viscosity of 35 40 centistokes at 25 C.,

C. 5.0 parts by weight silica, and

D, 5.0 parts by weight ammonia.

2. The antifoaming agent as recited in claim 1 which consistsessentially of a mixture of A. 100 parts by weight mineral oil, B. 1.0part by weight of a benzene soluble organopolysiloxane resin consistingof (CH3)3SiO1/2 units and SiO2 units in which the ratio of (CH3)3SiO1/2units to the SiO2 units is within the range from 0.6/1 to 1.2/1, C 2.5parts by weight silica, and D 1.0 part by weight hexamethyldisilazane.3. The antifoaming agent as recited in claim 1 which consistsessentially of a mixture of A 100 parts by weight mineral oil, B 2.0parts by weight of a benzene soluble organopolysiloxane resin consistingof (CH3)3SiO1/2 units and SiO2 units in which the ratio of (CH3)3SiO1/2units to the SiO2 units is within the range from 0.6/1 to 1.2/1, C 5.0parts by weight methylsilsesquioxane gel, and D 0.02 part by weight KOH.4. The antifoaming agent as recited in claim 1 which consistsessentially of a mixture of A. 100 parts by weight dioctyl phthalate, B.5.0 parts by weight hydroxyl endblocked dimethylpolysiloxane fluidhaving a viscosity of 35 - 40 centistokes at 25* C., C. 5.0 parts byweight silica, and D. 5.0 parts by weight ammonia.